You probably need to post more information in order to get good feedback. Here are just some of the questions that you might want to post:
1) Which inks are you using?
2) Are you using a RIP or the driver? If a RIP, which RIP?
3) What graphic software program (Corel, Photoshop,...)are you printing from?
4) What is the color management settings in the graphic software set to?
5) What are your settings in the RIP or the driver?
6) What types of shirts (name brand, fabric, color,...) are you using?
7) Are you using pretreatment? If so, what is your pretreatment process?
8) Have you run a nozzle check? If so, what did it look like.
All of the items above can have an effect on your colors. Thus, the reason for knowing this before giving you good advice and not just sending you on a wild goose chase. I am sure if you call tech support, they would ask the same if not similar questions.
Mark